In recent years, Package-on-Package (hereinafter referred to as “PoP”) semiconductor apparatuses have been used in mobile phones, digital cameras, mobile personal computers, and the like. As a semiconductor device to be used in a semiconductor apparatus with a three-dimensional mounting structure such as a PoP semiconductor apparatus, various low-profile/small-sized semiconductor devices that allow other semiconductor devices to be stacked on top are being proposed.
A conventional semiconductor device enabling another semiconductor device to be stacked on top includes: a substrate; a semiconductor element mounted on one face (hereinafter referred to as a “front face” or a “substrate front face”) of the substrate; a molding resin portion that molds the semiconductor element mounted on the substrate with resin; and a projected electrode formed in a region outside of a resin-molded region of the substrate. As shown, conventionally, the projected electrode for providing electrical connection to another semiconductor device to be stacked is formed in the region outside of the resin-molded region of the substrate. However, when a resin-molded region and a region not molded with resin exist on a substrate, warpage disadvantageously occurs on the substrate. In this light, a technique has been proposed for molding, with resin, the entire front face of a substrate on which a semiconductor element and a projected electrode are disposed.
For example, the following technique is disclosed in Japanese Patent Laid-Open No. 2003-174048. First, a semiconductor element is mounted on one face (front face) of a flexible substrate. Next, a projected electrode that protrudes beyond the semiconductor element is provided and, at the same time, on the other face of the substrate (the face on the opposite side of the front face: hereinafter referred to as a “rear face”), a rear face electrode is formed at a position corresponding to the formation position of the projected electrode. In this case, a stud rod with a flat distal end-face and a cylindrical body is used as the projected electrode. More specifically, a small diameter portion of the stud rod is inserted into a penetrating hole of the substrate, and a soldering paste is injected into the penetrating hole to form a junction at which conduction is achieved between a wiring pattern and the stud rod. At this point, the rear face electrode is formed using the soldering paste injected into the penetrating hole.
The substrate is then set in a molding mold in which an elastic body such as silicon rubber is disposed in advance on a molding face. By performing compression molding on resin supplied to a front face-side of the substrate, a molding resin portion is formed which molds the semiconductor element and the projected electrode with resin. At this point, the substrate is deformed by the compression force during resin molding so as to cause the rear face electrode to protrude. In addition, an end of the projected electrode is brought into close contact with the elastic body by the compression force during resin molding. Consequently, the end of the projected electrode can be projected from an upper face of the molding resin portion while preventing resin from adhering to the end of the projected electrode during resin molding.
In addition, for example, the following technique is disclosed in Japanese Patent Laid-Open No. 2004-296555. First, a wafer with bumps formed on the principal face of the wafer is set inside upper and lower molds in which a strippable film has been adhered to a molding face. Next, compression molding is performed on a silicone rubber composition for molding or a liquid thermosetting epoxy resin composition supplied to a principal face-side of the wafer. Consequently, since the compression force during resin molding causes ends of the bumps to adhere to the strippable film, the ends of the bumps can be projected from an upper face of a molding resin portion.
Furthermore, for example, the following technique is disclosed in Japanese Patent Laid-Open No. 2004-327855. A description on the technique will now be given with reference to FIG. 31.
First, a projected electrode 103 is formed on a laminated land 102 formed on the front face of a substrate 101. A semiconductor element 104 is then mounted in an element mounting region on the front face of the substrate 101. Next, a connecting terminal 105 formed on the front face of the substrate 101 and an electrode terminal 106 formed on the principal face of the semiconductor element 104 are electrically connected to each other via a thin metallic wire 107. The substrate 101 is then set in a molding mold in which an elastic tape 108 is attached in advance to a molding face (inner face) of the mold. Next, in a state where an end of the projected electrode 103 is embedded into the elastic tape 108, a molding resin portion 109 that molds the semiconductor element 104 and the projected electrode 103 with resin is transfer-molded. The elastic tape 108 attached to an upper face of the molding resin portion 109 of a molded body extracted from the molding mold is then stripped away. Consequently, the end of the projected electrode 103 can be projected from the upper face of the molding resin portion 109. Subsequently, a rear-face projected electrode 111 is formed on a rear-face land 110 formed on the rear face of the substrate 101.
Moreover, for example, the following technique is disclosed in Japanese Patent Laid-Open No. 2002-359323. A description on the technique will now be given with reference to FIG. 32.
First, a projected electrode 203 is formed on a laminated land 202 formed on the front face of a substrate 201. A semiconductor element 204 is then mounted in an element mounting region on the front face of the substrate 201. Next, a connecting terminal 205 formed on the front face of the substrate 201 and an electrode terminal 206 formed on the principal face of the semiconductor element 204 are electrically connected to each other via a thin metallic wire 207. The substrate 201 is then set in a molding mold. Next, a molding resin portion 208 that molds the semiconductor element 204 and the projected electrode 203 with resin is transfer-molded. Next, an upper portion of the molding resin portion 208 of a molded body extracted from the molding mold is cut off. Consequently, a flattened distal end face of the projected electrode 203 can be exposed from an upper face of the molding resin portion 208. Subsequently, a rear-face projected electrode 210 is formed on a rear-face land 209 formed on the rear face of the substrate 201.
Furthermore, Japanese Patent Laid-Open No. 2003-174124 discloses another technique of exposing a flattened distal end face of a projected electrode from an upper face of a molding resin portion. First, a projected electrode for external electrode formation is formed on a substrate with a semiconductor element joined to a front face thereof. The substrate is then set in a molding mold. Next, by performing compression molding on resin supplied to a front face-side of the substrate, a molding resin portion is formed which molds the semiconductor element and the projected electrode with resin. At this point, the compression force during resin molding compresses the projected electrode using an inner face (molding face) of the molding mold so as to squash the projected electrode by at least 5 percent. Consequently, the flattened distal end face of the projected electrode can be exposed from the upper face of the molding resin portion.